1. Field of the Invention
The present invention relates to a centrifugal fan device.
2. Description of the Related Art
Conventionally, there is known a centrifugal fan device for rotating an impeller with the drive power of a motor and discharging an axially drawn gas in a circumferential direction. The centrifugal fan device is used as, e.g., a suction means for a cleaner or an air cooling means for an electronic device.
A structure of a conventional centrifugal fan device is disclosed in, e.g., U.S. Patent Application Publication No. 2008/0069689 A1 (hereinafter US 2008/0069689). The centrifugal fan device of US 2008/0069689 includes a housing, an impeller arranged within the housing, and a drive device for rotating the impeller (see, for example, Claim 1 and FIGS. 1A and 3B of US 2008/0069689). In the centrifugal fan device of US 2008/0069689, a drawing hole is formed in a top shell of the housing (see, for example, Claim 5 and FIGS. 1A and 3B of US 2008/0069689).
In the centrifugal fan device disclosed in US 2008/0069689, a groove is formed on the lower surface of the top shell around the drawing hole. The upper end portion of a top panel of the impeller is inserted into the groove (see, for example, FIG. 3B of US 2008/0069689). However, with the structure of US 2008/0069689, the vibrations and noises of the top shell grow larger around the drawing hole. In particular, the problem of vibrations and noises becomes severe when driving the centrifugal fan device at a high speed.